The present invention relates to inherently flame resistant (FR) polyester fabrics and to a system for imparting soil, fluid, or microbial resistance properties to inherently flame resistant fabrics while substantially maintaining the flame resistant properties of the fabric. Inherently flame resistant polyester has been produced for applications where durable flame resistance is required. The flame resistance of the polyester is the result of incorporating an organic phosphorous compound into the polyethylene terephthalate chain during the fiber production process.
The flame resistant effect of incorporating this copolymer into a fiber results from two physical properties. First, incorporation of the copolymer makes it difficult for combustion to take place because the incorporated copolymer gives the polyester fabric a lower melting point than regular polyester. Thus, the polyester, which is a thermoplastic material, melts and shrinks away from flames. Second, if any burning does take place during the shrinkage from the flame, the phosphorous component prevents the melting drips from burning by influencing the composition of the pyrolisis gases.
Since the chemical flammability resistance is built into the polyethylene terephthalate chain, the flammability properties will not wash or dry clean out during laundering as long as proper washing procedures are followed. In contrast, topically applied flame resistant treatments are known to wash off with laundering, resulting in inconsistent flame resistant behavior over the life of the textile. Additionally, topically treated fabrics are susceptible to inconsistency of application of the FR additive, causing variable flammability results.
Inherently flame resistant polyester fabrics, including knits, wovens, and non-woven fabrics, have found a market in such diverse areas as bedding, draperies, clothing, and particularly for hospitality and medical uses. The inherent FR fabrics used in the medical, hospitality and clothing areas would also benefit from having additional properties such as soil and stain resistance and/or resistance to the growth of bacteria, fungi, yeast or algae.
Stain resistance, microbial resistance and water repellency are desirable qualities to have in many textile materials. In restaurants, for example, tablecloths are often subject to rapid water penetration and frequent staining. Hospitals also have a need to prevent staining and microbial growth on their linens, due to appearance and health-related concerns. These properties necessitate frequent cleaning and/or replacement of such items, leading to a loss of time and money.
The prior art, however, denied these users access to fabrics that are inherently FR and treated to provide these additional desirable properties. Manufacturers of inherently flame resistant fibers have specifically warned against adding chemical treatments to their fabrics because of the potential loss of the flame resistance properties. Kosa, Inc., the manufacturer of the trademarked AVORA(trademark) for flame resistant fibers, wars that acrylic resins, silicone and fluorocarbon compounds should be avoided because of their potential for damaging the inherent flame resistant properties of the AVORA(trademark) fabric. See Kosa, xe2x80x9cAVORA(trademark) FRxe2x80x9d publication, p.6. Therefore, inherently flame resistant polyester fabrics are sold scoured substantially fee from intentional or non-intentional chemical treatments. AVORA(trademark) FR (Kosa polyester and TREVIRA(trademark) CS (Trevira) polyester are examples of polyethylene terephthalate incorporating organic phosphorous compounds in the fiber resulting in the resulting polyester being inherently flame retardant.
Hospitals and restaurants, in particular, have a need for inherently flame resistant linens in order to provide a safe environment for their patients and patrons. Yet these industries have no way to obtain inherently flame resistant linens with additional chemical treatments for stain resistance, microbial resistance and water repellency.
Thus, there remains a need for imparting stain, fluid and microbial resistance properties in inherently flame resistant fabric while substantially maintaining the fabric""s original flame resistant characteristics.
The present invention provides an a textile article having flame resistant properties comprising a plurality of inherently flame resistant fibers formed into a fabric, and a finish on the fabric, wherein the finish imparts a property selected from the group consisting of an antimicrobial agent, a soil repellant and a fluid repellant.
In the present invention, the inherently flame resistant fiber is first made into a fabric. Any of the known methods of doing so, including weaving, knitting and non-woven fabric formation can be used. Other techniques such as tufting may also be adopted.
Once the fabric is formed, it is scoured prior to the application of the chemical treatments. Scouring removes residual processing aids, which may be present on the textile material, as well as dirt and/or oily materials. The scouring of the textile material to remove any residual textile processing aids, dirt, oil residues, and the like, can be readily accomplished by passing the textile material through an aqueous detergent. After passing the textile material through the aqueous detergent, it should be in order to remove any residual detergent.
The amount of the detergent constituent employed in the aqueous detergent containing solution can vary widely as can the type of detergent. Generally, desirable results can be obtained when the amount of the detergent constituent employed is from about 0.10 to about 1.0 weight percent, based on the total weight of the detergent solution. The detergent to be employed is typically selected from a group that does not react negatively with the fabric to be scoured or with the fabric""s flame resistant properties. Typical examples of suitable detergents that can be employed in the detergent scouring of the textile material, include SOLPON 1159(trademark) SOLPON SPI(trademark), and PICOSCOUR JET(trademark).
After the fabric has been scoured and rinsed, the scoured material may then be subjected to a chemical treatment step. The chemical treatment of the present invention comprises exposing the inherently FR textile material to an aqueous solution of a wetting agent and a flame retardant and one or more of: an antimicrobial agent, a water repellant agent, or a soil resistance agent.
While, not wishing to be bound to a particular theory, a flame retardant may be added to the chemical treatment composition to ensure that the inherent flame retardant remains chemical coupled with the polyester fiber. It is thought that the presence of the flame retardant in the chemical coating composition may help to kinetically drive the inherently coupled flame retardant to remain chemically bound within the polyethylene terephthalate chain of the polyester fibers. The flame retardant in the chemical coating composition is preferably the same flame retardant that comprises the inherently flame retardant fabric. Typical examples of suitable flame-retardants include Cyclic Phosphonate, APEX FLAMEPROOF #1525(trademark), PYRON N-75(trademark), and ANTIBLAZE NT(trademark). The flame retardant to be added to the chemical treatment preferably comprises about 2% to about 10% by weight of the chemical treatment composition. More preferably, the flame retardant comprises about 4.8% by weight of the chemical treatment composition.
The wetting agent of the chemical coating composition reduces the hydrophobicity of the dry fabric and to ensure that the entire fabric is sufficiently contacted with all the chemical treatments. The wetting agent to be added to the chemical treatment preferably comprises between about 0.5% to about 2.0% by weight of the chemical treatment composition. More preferably, the wetting agent comprises about 0.96% by weight of the chemical treatment composition. Preferably, the wetting agent is au alcohol, More preferably, the wetting agent is an aliphatic alcohol such as Isopropanol. Typical examples or suitable wetting agents include Nonionic Ethylene Ether Condensates, such as DEXOPAL 555(trademark), or Aqueous Cationic Non-rewetting surfactants solutions, such as MYKON NRW(trademark).
For those cases where antimicrobial properties are desired, an antimicrobial agent is added to the chemical treatment to reduce the growth of microorganisms on the inherently flame resistant fabric. By xe2x80x9cantimicrobial agentxe2x80x9d is meant any substance or combination of substances that kills or prevents the growth of microorganisms, and includes antibiotics, antifungal, antiviral and antialgal agents. The antimicrobial agent can be either a xe2x80x9cleachingxe2x80x9d antimicrobial agent or a xe2x80x9cmolecularly bondedxe2x80x9d antimicrobial agent. Leaching antimicrobials work by leaching or moving from the surface of the fabric to contact and kill a nearby microorganism. Molecularly bonded antimicrobial agents work by remaining affixed to the fabric and kill the microorganism as it contacts the surface to which the bonded antimicrobial has been applied. See White et al., xe2x80x9cA Comparison of antimicrobials for the Textile Industryxe2x80x9d, www.microbeshield.com.
The antimicrobial agent to be added to the chemical treatment composition preferably comprises about 0.20% to about 2.0% by weight of the chemical treatment composition. More preferably, the antimicrobial agent comprises about 0.48% by weight of the chemical treatment composition. Typical examples of suitable antimicrobial agents include ULTRAFRESH DM 25(trademark), an octilinone or BIOSHIELD AM 500, an organosilane. Preferably, the antimicrobial agent is a xe2x80x9cmolecularly bondedxe2x80x9d antimicrobial agent. More preferably, the antimicrobial agent is an organofuctional silane. Even more preferably, the antimicrobial agent is an organosilane composition comprising about 16% by weight of chloropropyltrihydroxysilane and about 84% by weight of Octadecylaminodimethyltrihydroxysilypropyl Ammonium Chloride, available from Aegis under the trademark AEM 5700(trademark).
For those cases where fluid or soil repellent properties are desired, a fluid or soil repellent agent is added to the chemical treatment composition to improve the fabric""s water repellency and the fabric""s resistance to staining. Also, a combination fluid repellent/soil resistant agent may be added to the chemical treatment composition. Preferably, in the present invention, the fluid repellent agent and soil resistant agent is added as a combination fluid repellent/soil resistant agent. More preferably, the fluid repellent/soil resistant agent is a fluorochemical. Even more preferably, the fluid repellent/soil resistant agent is a fluorochemical available from Dupont under the trademark ZONYL 7040(trademark), which is a water based dispersion of fluorinated acrylic co-polymer. The combination fluid repellent/soil resistant agent to be added to the chemical treatment preferably comprises about 2% to about 10% by weight of the chemical treatment composition. More preferably, the fluid repellent/soil resistant agent comprises about 3.6% by weight of the chemical treatment composition.
The chemical treatment may be applied by various methods known in the art, such as by spraying, dipping or pad application. In a preferred embodiment, the chemical treatment is applied to the scoured fabric using a pad applicator. The pressure of the squeeze rollers is controlled to achieve a wet pick-up of between about 25% and about 60% of the chemical treatment. Preferably, the pressure of the squeeze rollers is controlled to achieve a wet pick-up of approximately 45% of the chemical composition. The chemically treated fabric is then dried through exposure to between about 320xc2x0 F. and 420xc2x0 F. for between about 20 seconds and 60 seconds in a hot air oven. Preferably, the fabric is dried through exposure to 380xc2x0 F. for 30 seconds in a hot air oven.